Once you learn how Adobe Analytics looks and is implemented on the page, it's fairly easy to spot issues with it that can be fixed. This is a strength in that it doesn't take a largely technical person to call out any issues during implementation.
Adobe Analytics is good with adding tracking to the page and providing strong and accurate analytics data for analysis.
There are numerous online tools to help with checking Adobe Analytics data for verification on a site. Firefox plugins such as Firebug, Omnibug, as well as any proxy debugger such as Fiddler and many others can be used.
It can take some time for someone to get comfortable with knowing what to look for when validating proper Adobe Analytics tags. I'm not sure if this is something that can be improved upon, it's just something that I have noticed can take some time when somebody is first learning how to check the tags.
Issues I find with implementation appear to be due to improperly inputting variables inside greater than and less than signs (<>). This may be more on the implementation side of things, but perhaps there is something that Adobe Analytics can do with alerting a developer that a variable is not receiving any values.
One big limitation with Adobe Analytics for me has been not being able to sort between different iPhone devices and iOS operating system versions. This is data that I always look for to see which users are accessing a site, but unfortunately Adobe Analytics doesn't appear to be able to filter this.
Positive impact is that the analytics data provided by Adobe Analytics allowed my former company to have great awareness on the most current browser and touch device usage that people were using to access our sites.
Positive impact is that the analytics department was able to provide a great range of information on how to approach a marketing campaign or strategy by targeting certain demographics that appeared to be interested in certain parts or aspects of the site.
Positive impact was increased employee efficiency, since we had better access to how to support customers and users accessing the site.
Adobe Analytics is a great tool and I have found Google Analytics to also provide good data. Adobe Analytics sitecatalyst website is not as user friendly as the Google Analytics website interface, in my opinion. However, I think that actual QA verification of Adobe Analytics on websites is easier.